Apparatus for controlling linear compressor and control method of apparatus for controlling linear compressor

Abstract

The present disclosure relates to a compressor control apparatus and a compressor control method thereof, and more particularly, to a compressor control apparatus for controlling a switching operation of a switching device to control the start-up of a compressor motor and a compressor control method thereof.

What is the claimed is: 
     
       1. A compressor control apparatus configured to control a compressor, the compressor control apparatus comprising:
 an input unit connected to an external power source and configured to convert alternating current (AC) power input from the external power source into direct current (DC) power, the input unit comprising a smoothing device configured to reduce variation of the DC power; 
 a motor that is a single phase motor; 
 an inverter unit comprising two pairs of switching devices that are connected to ends of the smoothing device of the input unit and to the motor, that are configured to convert the DC power received from the smoothing device to driving power through a switching operation, and that are configured to apply the driving power to the motor; 
 a sensing unit connected between the input unit and the inverter unit and configured to sense a motor current applied to the motor; and 
 a control unit configured to:
 receive the motor current sensed by the sensing unit, 
 based on the motor current, generate a pulse width modulation (PWM) control signal for controlling operation of the switching devices, and 
 apply the PWM control signal to the switching devices to control operation of the switching devices, 
 
 wherein the control unit is further configured to:
 based on the motor current at a start-up of the motor, control operation of the switching devices (i) in a bipolar PWM switching mode in which the PWM control signal is configured to change between a plurality of polarities or (ii) in a unipolar PWM switching mode in which the PWM control signal is configured to change between zero and one of the plurality of polarities, 
 during a reference time period subsequent to the start-up of the motor, increase a motor voltage applied to the motor and control operation of the switching devices in the bipolar PWM switching mode, 
 subsequent to the reference time period, switch operation of the switching devices from the bipolar PWM switching mode to the unipolar PWM switching mode, and 
 based on the motor voltage being less than a reference voltage subsequent to the reference time period, switch operation of the switching devices from the unipolar PWM switching mode to the bipolar PWM switching mode. 
 
 
     
     
       2. The compressor control apparatus of  claim 1 , wherein the control unit is further configured to, based on the motor current being less than a reference current, control operation of the switching devices in the bipolar PWM switching mode. 
     
     
       3. The compressor control apparatus of  claim 2 , wherein the control unit is further configured to, based on the motor current being greater than or equal to the reference current, control operation of the switching devices in the unipolar PWM switching mode. 
     
     
       4. The compressor control apparatus of  claim 1 , wherein the control unit is further configured to, based on the motor voltage being greater than or equal to the reference voltage, control operation of the switching devices in the unipolar PWM switching mode. 
     
     
       5. A method of controlling a compressor control apparatus configured to control a compressor, the compressor control apparatus including an input unit configured to convert alternating current (AC) power input from an external power source into direct current (DC) power, the input unit including a smoothing device configured to reduce variation of the DC power, a motor that is a single phase motor, an inverter unit including two pairs of switching devices that are connected to ends of the smoothing device of the input unit and to the motor, that are configured to convert the DC power received from the smoothing device to driving power through a switching operation, and that are configured to apply the driving power to the motor, a sensing unit configured to sense a motor current applied to the motor, and a control unit configured to receive the motor current sensed by the sensing unit, generate a pulse width modulation (PWM) control signal for controlling operation of the switching devices, and control operation of the switching devices by the PWM control signal based on the motor current at a start-up of the motor, the method comprising:
 applying the driving power to the motor to start the motor; 
 during a reference time period subsequent to the start-up of the motor, controlling operation of the switching devices in a bipolar PWM switching mode in which the PWM control signal is configured to change between a plurality of polarities; and 
 subsequent to the reference time period, controlling operation of the switching devices based on the motor current at the start-up of the motor (i) in the bipolar PWM switching mode or (ii) in a unipolar PWM switching mode in which the PWM control signal is configured to change between zero and one of the plurality of polarities, 
 wherein controlling operation in the bipolar PWM switching mode comprises:
 during the reference time period subsequent to the start-up of the motor, increasing a motor voltage applied to the motor. 
 
 
     
     
       6. The method of  claim 5 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 comparing the motor current sensed by the sensing unit with a reference current; and 
 based on a result of the comparison of the motor current with the reference current, controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode. 
 
     
     
       7. The method of  claim 6 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor current being less than the reference current, maintaining operation of the switching devices in the bipolar PWM switching mode. 
 
     
     
       8. The method of  claim 6 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor current being greater than or equal to the reference current, switching operation of the switching devices from the bipolar PWM switching mode to the unipolar PWM switching mode. 
 
     
     
       9. The method of  claim 8 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor current being less than the reference current in a state of controlling operation of the switching devices in the unipolar PWM switching mode, switching operation of the switching devices from the unipolar PWM switching mode to the bipolar PWM switching mode. 
 
     
     
       10. The method of  claim 5 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 comparing the motor voltage applied to the motor with a reference voltage; and 
 based on a result of the comparison of the motor voltage to the reference voltage, controlling operation of the switching devices in the bipolar PWM switching mode or the unipolar PWM switching mode. 
 
     
     
       11. The method of  claim 10 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor voltage being less than the reference voltage, maintaining operation of the switching devices in the bipolar PWM switching mode. 
 
     
     
       12. The method of  claim 10 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor voltage being greater than or equal to the reference voltage, switching operation of the switching devices from the bipolar PWM switching mode to the unipolar PWM switching mode. 
 
     
     
       13. The method of  claim 12 , wherein controlling operation of the switching devices in the bipolar PWM switching mode or in the unipolar PWM switching mode comprises:
 based on the motor voltage being less than the reference voltage in a state of controlling operation of the switching devices in the unipolar PWM switching mode, switching operation of the switching devices from the unipolar PWM switching mode to the bipolar PWM switching mode.